/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkGradientMagnitudeRecursiveGaussianImageFilter_hxx
#define itkGradientMagnitudeRecursiveGaussianImageFilter_hxx

#include "itkGradientMagnitudeRecursiveGaussianImageFilter.h"
#include "itkImageRegionIterator.h"
#include "itkProgressAccumulator.h"
#include "itkMath.h"

namespace itk
{
/**
 * Constructor
 */
template <typename TInputImage, typename TOutputImage>
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage,
                                              TOutputImage>::GradientMagnitudeRecursiveGaussianImageFilter()
{
  m_NormalizeAcrossScale = false;

  m_DerivativeFilter = DerivativeFilterType::New();
  m_DerivativeFilter->SetOrder(EnumGaussianOrderType::FirstOrder);
  m_DerivativeFilter->SetNormalizeAcrossScale(m_NormalizeAcrossScale);
  m_DerivativeFilter->InPlaceOff();
  m_DerivativeFilter->ReleaseDataFlagOn();

  for (unsigned int i = 0; i < ImageDimension - 1; i++)
  {
    m_SmoothingFilters[i] = GaussianFilterType::New();
    m_SmoothingFilters[i]->SetOrder(EnumGaussianOrderType::ZeroOrder);
    m_SmoothingFilters[i]->SetNormalizeAcrossScale(m_NormalizeAcrossScale);
    m_SmoothingFilters[i]->InPlaceOn();
  }

  m_SmoothingFilters[0]->SetInput(m_DerivativeFilter->GetOutput());
  for (unsigned int i = 1; i < ImageDimension - 1; i++)
  {
    m_SmoothingFilters[i]->SetInput(m_SmoothingFilters[i - 1]->GetOutput());
  }

  m_SqrSpacingFilter = SqrSpacingFilterType::New();
  m_SqrSpacingFilter->SetInput(1, m_SmoothingFilters[ImageDimension - 2]->GetOutput());
  // run that filter in place for much efficiency
  m_SqrSpacingFilter->InPlaceOn();

  // input of SqrtFilter is the cumulative image - we can't set it now
  m_SqrtFilter = SqrtFilterType::New();
  m_SqrtFilter->InPlaceOn();

  this->SetSigma(1.0);
  this->InPlaceOff();
}

template <typename TInputImage, typename TOutputImage>
void
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::PrintSelf(std::ostream & os,
                                                                                    Indent         indent) const
{
  Superclass::PrintSelf(os, indent);
  os << "NormalizeAcrossScale: " << m_NormalizeAcrossScale << std::endl;
  os << "Sigma: " << m_DerivativeFilter->GetSigma() << std::endl;
}

/**
 * Set value of Sigma
 */
template <typename TInputImage, typename TOutputImage>
void
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::SetSigma(RealType sigma)
{
  if (Math::NotExactlyEquals(sigma, this->GetSigma()))
  {
    for (unsigned int i = 0; i < ImageDimension - 1; i++)
    {
      m_SmoothingFilters[i]->SetSigma(sigma);
    }
    m_DerivativeFilter->SetSigma(sigma);

    this->Modified();
  }
}

template <typename TInputImage, typename TOutputImage>
typename GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::RealType
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::GetSigma()
{
  // just return the sigma value of one filter
  return m_DerivativeFilter->GetSigma();
}

template <typename TInputImage, typename TOutputImage>
void
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::SetNumberOfWorkUnits(ThreadIdType nb)
{
  Superclass::SetNumberOfWorkUnits(nb);
  for (unsigned int i = 0; i < ImageDimension - 1; i++)
  {
    m_SmoothingFilters[i]->SetNumberOfWorkUnits(nb);
  }
  m_DerivativeFilter->SetNumberOfWorkUnits(nb);
  m_SqrSpacingFilter->SetNumberOfWorkUnits(nb);
  m_SqrtFilter->SetNumberOfWorkUnits(nb);
}

/**
 * Set Normalize Across Scale Space
 */
template <typename TInputImage, typename TOutputImage>
void
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::SetNormalizeAcrossScale(bool normalize)
{
  if (m_NormalizeAcrossScale != normalize)
  {
    m_NormalizeAcrossScale = normalize;

    for (unsigned int i = 0; i < ImageDimension - 1; i++)
    {
      m_SmoothingFilters[i]->SetNormalizeAcrossScale(normalize);
    }
    m_DerivativeFilter->SetNormalizeAcrossScale(normalize);

    this->Modified();
  }
}

//
//
//
template <typename TInputImage, typename TOutputImage>
void
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::GenerateInputRequestedRegion()
{
  // call the superclass' implementation of this method. this should
  // copy the output requested region to the input requested region
  Superclass::GenerateInputRequestedRegion();

  // This filter needs all of the input
  typename GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::InputImagePointer image =
    const_cast<InputImageType *>(this->GetInput());
  if (image)
  {
    image->SetRequestedRegion(this->GetInput()->GetLargestPossibleRegion());
  }
}

//
//
//
template <typename TInputImage, typename TOutputImage>
void
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::EnlargeOutputRequestedRegion(
  DataObject * output)
{
  auto * out = dynamic_cast<TOutputImage *>(output);

  if (out)
  {
    out->SetRequestedRegion(out->GetLargestPossibleRegion());
  }
}

/**
 * Compute filter for Gaussian kernel
 */
template <typename TInputImage, typename TOutputImage>
void
GradientMagnitudeRecursiveGaussianImageFilter<TInputImage, TOutputImage>::GenerateData()
{
  itkDebugMacro(<< "GradientMagnitudeRecursiveGaussianImageFilter generating data ");

  const typename TInputImage::ConstPointer inputImage(this->GetInput());

  typename TOutputImage::Pointer outputImage(this->GetOutput());

  // Create a process accumulator for tracking the progress of this minipipeline
  ProgressAccumulator::Pointer progress = ProgressAccumulator::New();
  progress->SetMiniPipelineFilter(this);

  // If the last filter is running in-place then this bulk data is not
  // needed, release it to save memory
  if (m_SqrtFilter->CanRunInPlace())
  {
    outputImage->ReleaseData();
  }


  typename CumulativeImageType::Pointer cumulativeImage = CumulativeImageType::New();
  cumulativeImage->SetRegions(inputImage->GetBufferedRegion());
  cumulativeImage->Allocate();
  cumulativeImage->FillBuffer(NumericTraits<InternalRealType>::ZeroValue());
  // The output's information must match the input's information
  cumulativeImage->CopyInformation(this->GetInput());

  m_DerivativeFilter->SetInput(inputImage);

  const unsigned int numberOfFilterRuns = ImageDimension * ImageDimension;
  progress->RegisterInternalFilter(m_DerivativeFilter, 1.0f / numberOfFilterRuns);

  for (unsigned int k = 0; k < ImageDimension - 1; k++)
  {
    progress->RegisterInternalFilter(m_SmoothingFilters[k], 1.0f / numberOfFilterRuns);
  }

  for (unsigned int dim = 0; dim < ImageDimension; dim++)
  {
    unsigned int i = 0;
    unsigned int j = 0;
    while (i < ImageDimension - 1)
    {
      if (i == dim)
      {
        j++;
      }
      m_SmoothingFilters[i]->SetDirection(j);
      i++;
      j++;
    }
    m_DerivativeFilter->SetDirection(dim);

    const double lambdaSpacing = inputImage->GetSpacing()[dim];
    m_SqrSpacingFilter->SetFunctor([lambdaSpacing](const InternalRealType & a, const InternalRealType & b) {
      return a + itk::Math::sqr(b / lambdaSpacing);
    });
    m_SqrSpacingFilter->SetInput(cumulativeImage);

    // run the mini pipeline for that dimension
    // Note: we must take care to update the requested region. Without that, a
    // second run of the
    // filter with a smaller input than in the first run trigger an exception,
    // because the filter
    // ask for a larger region than available. TODO: there should be a way to do
    // that only once
    // per GenerateData() call.
    m_SqrSpacingFilter->UpdateLargestPossibleRegion();

    // and user the result as the cumulative image
    cumulativeImage = m_SqrSpacingFilter->GetOutput();
    cumulativeImage->DisconnectPipeline();
  }
  m_SqrtFilter->SetInput(cumulativeImage);
  m_SqrtFilter->GraftOutput(this->GetOutput());
  m_SqrtFilter->UpdateLargestPossibleRegion();
  this->GraftOutput(m_SqrtFilter->GetOutput());
}
} // end namespace itk

#endif
